By Tom Royer, OSU Extension Entomologist

Our Plant Disease and Insect Diagnostic lab received samples of wheat that were damaged by brown wheat mites. Producers need to remain alert so that they don’t mistake damaged wheat from brown wheat mite for drought or virus disease.

Brown wheat mite is small (about the size of this period.) with a metallic brown to black body and 4 pair of yellowish legs. The forelegs are distinctly longer that the other three pair. Brown wheat mites can complete a cycle in as little as 10-14 days. Brown wheat mite causes problems in wheat that is stressed from lack of moisture. They feed by piercing plant cells in the leaf, which results in “stippling”. As injury continues the plants become yellow, then dry out and die. They are very susceptible to hard, driving rains which many areas have now experienced, but until then they can cause yield loss when present in large numbers.

A closeup of a brown wheat mite. Photo courtesy Franklin Peairs, CSU.

Brown what mite can severely damage wheat that is already stressed due to drought or other adverse environmental conditions.

Brown wheat mites are about the size of a period at the end of a sentence and can be difficult to see with the naked eye.

We typically experience 3 generations per year. However, in this sample, the mites had already caused considerable damage and had laid significant numbers of diapausing white eggs that tell us they have completed their last generation of the growing season and these eggs will oversummer.

Brown wheat mite eggs in soil.

Research suggests that a treatment threshold of 25-50 brown wheat mites per leaf in wheat that is 6-9 inches tall is economically warranted. An alternative estimation is “several hundred” per foot of row. If you find active brown wheat mites in your field, check CR-7194, Management of Insect and Mite Pests in Small Grains for registered insecticides, application rates, and grazing/harvest waiting periods. It can be obtained from any County Extension Office, or found at www.wheat.okstate.edu